IT IS the grassroots movement that has grown into a political force strong enough to shutdown the wealthiest government in the world.

Now just 24 hours away from an unprecedented US default, Tea Party conservatives are still holding firm on their demands to defund ObamaCare before raising the debt ceiling.

So who are the Tea Party and what do they want?

Rather than an actual political party, the Tea Party is a grassroots movement based on the ideology of small government, personal freedoms and a number of core beliefs around military spending, family values and gun control.

The name comes from the famous 1773 Boston Tea Party tax protest and is also thought to be an acronym for taxed enough already - a common political mantra.

United States Studies Centre US politics lecturer Dr Adam Lockyer said the group is large, wealthy and based mainly in America's southern states.

"It's often said the Republicans in Arizona were the Tea Party before the Tea Party was around."

Republican senators walk back to their bus after meeting with President Obama. Picture: AP Photo, Charles Dharapak.Source:AP

Where did they come from?

The group has a long tradition in American political culture but their recent incarnation was galvanised by the election of President Barack Obama in 2008.

"A lot of them took the election of Obama as an affront. Not necessarily on racial lines but they saw him as an outsider, liberal elite and a threat to their way of life. It was a rally cry for the Tea Party movement and gave them something to mobilise around," Dr Lockyer said.

Support has grown through conservative lobby organisations like Generation Opportunity, Young Americans for Liberty and Freedom Partners, funded by the billionaire Koch brothers.

They even have an Australian spin off pushing for corporal punishment and tougher refugee policy.

Senator Mike Lee has been a major ally of Ted Cruz in the shutdown. Picture: AP Photo, Jose Luis MaganaSource:AP

Who are the key players?

Dr Lockyer said it was tricky to formally identify Tea Party candidates as politicians can align themselves with the movement at different times according to their objectives.

"How many tea partiers there are it's impossible to say, they're not card carrying members. … It's a loose network more than anything else," he said.

Ted Cruz has been the main face of the Tea Party movement in the current shutdown debate, regularly stating he will do everything possible to defund ObamaCare before Americans get "hooked on the sugar" of subsidised healthcare, Rolling Stone reports.

Strategists outside the government are also playing an important role. The Wall St Journal reports Michael Needham, the 31-year-old president of a conservative think tank has spent months rallying conservatives around the country to repeal the law.

"It has been on the front page of every newspaper. The polls show ObamaCare's more unpopular than ever. People are starting to wake up that it isn't going to work at all," he said.

Former Alaska governor Sarah Palin has been a vocal supporter of Ted Cruz.Source:AP

Is it working?

On one hand, Tea Party efforts have worked in that their refusal to compromise has led to a shutdown of the US government and taken debt ceiling negotiations to within a day of default.

It's also helping to gain popularity for its champions, with a recent Gallup poll shows Cruz's name recognition in the US has risen from just over 40 per cent to just over 60 per cent during the course of the shutdown.

On the other hand, their actions have driven a wedge through the heart of the Republican party with moderate conservatives such as John McCain and Peter King openly criticising their more extreme counterparts.

"Ted Cruz led us down this path. This was a disaster from the start, I could have predicted this, and this is what the leadership predicted three weeks ago when they said they would never pursue defending because it was going to work against us and we'd be blamed," New York Republican Peter King told the media earlier this week.